Electric furnace



Jari. 9, 1934. R. SCHMITZ 1,942,981

ELECTRIC FURNACE R. scHMlTz 1,942,981

ELECTRI C FURNAGE Jan. 9, 1934.

2 Sheets-Sheetv 2 Filed Deo. 14. 1929 Je .e441 '5 f7 e4 l w "M PatentedJan. 9, 1934 PATENT ori-lcs ELECTRIC FURNACE Rudolf Schmitz, Herne,Germany Application December 14, 1929, Serial No. 414,093, and inGermany December 16, 1928 7 Claims.

The present invention is a universal electric resistance furnace 'whichis characterized by the fact that it comprises two superposed heatingchambers, which can be utilized separately or combined for a series ofdifferent processes, such for example: melting out the wax, preliminaryheating,` smelting, casting, alloying, soldering, and burning porcelain.

On the accompanying drawings two forms of embodiment have been shown,and on these drawings:

Fig. 1 is a vertical longitudinal section of the universal furnace,

Fig. 2 is similar section through the double furnace in a larger scalebut without the standard.

Fig. 3 is a detail section of the flask arranged in inverted positiontogether with the auxiliary tube and stand and the model pin supportingcone as arranged for melting and discharging $0 the wax from the model.

Fig. 4 is a front and Fig. 5 a side view of the universal furnace,

Fig. 6 is a longitudinal section through an auxiliary heating device forthe process of soldering and melting out.

The universal furnace for melting, casting and alloying on the one side,and the burning out, preliminary heating, porcelain baking v andsoldering, according to Figs. 1-6, comprises a $0 suitable standard onwhich is fitted the body or part a1 of fire proof material. This part ishereafter referred to as a Silit-furnace. This upper part a1 ofrectangular or cylindrical section has the sectional form shown in Figs.1 and 2 and is provided with a chambera which at the top opens into alarger one a2. A receptacle e1 is detachably fitted in the chamber a2and is filled with an insertion fitting e of non-conducting material.This insertion fitting'e contains an auxiliary furnace b. The insertionfitting e can be exchanged for other parts (Fig. 6), while the chamber aserves for the reception of suitable asks or models. In order to securea tight insertion of the element e, its container e1 has a dependingannular flange 15 which fits into an annular groove 14 of the body a1.For the melting, casting and alloying the body al is utilized i. e. thechamber a in combination with the electrically heated cover e1, e. Theinsertion fitting e contains a fire proof tube d, closed at the upperend by a cap l1 having an observation opening l2 and containing a plateof mica Z which is held in close contact with the upper end of the tubed by the cap. Said tube is of inverted truncated conical form, and itslower portion is cylindrical as shown. The lower part forms the meltingor auxiliary furnace b and has on its circumference a winding ofplatinum wire 5 which constitutes the heating device. The second outertube d1 is intended to center and to fasten the rst mentioned tube d.

At the upper part of the tube d enters the compressed air passage mwhich surrounds the tub d1 with its windings 2 and which contains thevalve 3. The heating of the compressed air is due to an ordinary heatingequipment 4 lodged between d1 and the helicoidal windings 2. Thisheating device produces a temperature of about 800.

The outer face of the bottom of the cover part is provided with anannular projection i (Figs. l, 2) which fits out into a similar grooveof the horizontal ange 40 of the flask and which contains a tighteningring of copper and asbestos.

The center part of the cover of the container e1 form a detachable cover41, so that the heating elements 4 and 5 can be removed. They areconnected by wires to the contact pins 16, 17 (Figs. 4 and 5).

'I'he ring h lying onvthe upper side of the chamber a can be attached bybolts y, which traverse the flange 40 of the mule and the bottom of thecontainer e1 with its rigid cover part. (Fig. 5.) These bolts traversesuitable vertical tubes, lodged within the embeddingA of the insertionpart e. By screwing on the wing nuts f of the bolts g, the metal ring h,wherein hangs the flask 42, is strongly pressed against the flange ofthe mufile and the latter against the bottom of `the insertion part e,so that an airtight fltting is guaranteed.

'7 is a tubular supporting device which is employed at the melting,casting and alloylng process and lines the melting furnace b nearly in acomplete manner.' It is made from fireproof thin material and has forits object to reinforce and to elongate the edge of the melting oralloying hearth level or block b (Figs. 1, l2, 3 and '7). In order toassure its fastening within the embedding composition 8 its under endhas a fiange.

During the embedding of the model 43 to be cast, there is utilized theauxiliary tube 7 and the stand c (Fig. 3) which is provided with acentral opening c2 which receives the cone c1 and the inverted tube '7,which must be well centered within the flask in order to occupy theexact position within the melting furnace b. The metallic cone c1supports the model pins and Serves to form the inner surface of thehearth gases.

level b. The flange c3 determinates the exact position of the mufiie 42.

The filling of the flask with embedding material 8 is made when theilask occupies the inverted position, shown in Fig. 3 and by introducingit through the opening 44.

For the melting out of the wax, the preliminary heating, burning ofporcelain and alloying, the Silit-furnace al, i. e. the furnace a isused in cornbination with the insulating part 45 (Fig. 6).

In the bottom of the furnace a, the walls whereof show heating elements46, is provided an aperture 11, which continues in a channel 12 and ametallic tube 9 attached by a saddle 13. The condensation of steamescaping from the moist embedding composition of .the flask takes placewithin the tube 9 surrounded by water jack r. The condensed water andmolten wai: drops into the vessel e.

The insulating part 45 Fig. 6 for the melting of wax and the preliminaryheating has a conicalchamber 45a closed at both ends by mica plates 10.

All above mentioned parts are situated with in the standard 2O byplacing the projecting edge 18 of the body block a1 on the T-ormed frame19 (Figs. l, 4 and 5). Within the inner side of the standard are placedthe electric wires, the resistances, the current converter, the pedal ufor driving an air pump (Figs. 4, 5) and its air conducting tube, goingto the blast bor: which occupies the bottom part of the element a1. Theair tubes m, m' are detachably connected together by the winged union 1.

The switchboard z, shown in Fig. 4 is provided with the usual switchesfor the different heating devices 4, 5 and 46 and with the necessaryapparatus, such as manometers, taps, etc. The connecting cables areplaced at the rear side of the standard.

The different processes are conducted in the following manner:

The metallic cone c1 and the short tube 'I are according to Fig. 3placed into the opening c2 of the stand c, the casting pins 43a for themodel 43 are attached by wax as at 43b to the cone c1, the flask 42 isplaced in inverted position on the support c andiilled with more or lessliquid embedding composition. After the hardening of the embedding massthe flask is lifted off and the pins are withdrawn.

For the melting out of the wax, the member e, e is ilrst removed fromthe furnace chamber c2 and the flask 42 is arranged in its invertedposition, Fig. 3, in the chamber a, into which is now introduced theinsulating element 45 (Fig. 6). The heating elements 46 produce therequired temperature and the melting of the wax begins. lit dropsthrough the channel 12 and the tube 9 into the collecting vessel s. Themoist steam or the embedding composition of the flask is condensedwithin the tube 9 and the water drops also into the vessel.

The i'la .r is uniformly heated and without danger or" the operatorbeing injured by the wax After the melting process the heating of the`flask is continued in order to raise its temperature to a desireddegree.

The flask is then removed and attached in the normal position (Figs. land 2) to the insulating element, e, e1 by the bolts g and the wingednuts f. After the insertion of the parts e. 42 into the chambers of thebody a1 the air conducting tubes m, m' are connected by the nut' 1.

The cast-metal is then put into the hearth b.

. The heating wire 4 is then switched into circuit to effect heating o!the compressed air containing pipe 2 connected to the container x whichis filled with compressed air by operating the air pump t. By increasingthe temperature of the heating element 5 of thefurnace b, which 8 hasalso been switched on, the casting metal in the hearth b is melted.

The contents of the hearthcan be observed through the mica plate 1, andwhen the metal is melted the blast valve 3 is opened and the 8 moltenmetal pneumatically forced into the ilask. After the molten metal hasnlled the hollow in the embedding composition of the asl; the threeheating elements of the Silit-furnace el, the furnace b and the air pipe2 are then switched 9 oi and the compressed air caused to escape byunscrewing the nut l.

The form of embodiment shown in Fig. 'I represents a tilting furnace,the principles of operation of which are similar to those of the furnace9 hereinbefore described.

I claim:

l. An electric furnace comprising a body having a lower chamber and anupper chamber of greater width than the lower chamber and into 10 whichthe latter opens, a flask arranged in the lower chamber and removabletherefrom, insert member removably mounted in the upper chamber saidflask being mounted on the bottom of said insert member, and a meltingfurnace in 10 said insert member, and arranged to discharge moltenmaterial into the flask.

2. An electric furnace comprising a body hat'- ing a lower chamber andan upper chamber of greater width than the lower chamber and into 11which the latter opens, a flask arranged in the lower chamber andremovable therefrom, an insert member removably mounted in the upperchamber said flask being mounted on the bottom of said insert member,and a melting 11 furnace in said insert member, arranged to dischargemolten material into the ilask, said insert member also having acompressed air discharge duct opening into the melting furnace.

3. An electric furnace comprising a body hav- 12 ing a lower chamber andan upper chamber oi greater width than the lower chamber and into whichthe latter opens, a ask arranged in the lower chamber and removabletherefrom, an insert member removably mounted in the up- 12 per chambersaid flask being mounted on the bottom of said insert member, a meltingfurnace in said insert member, arranged tc discharge molten materialinto the flask, said insert member also having a compressed airdischarge duct 13 opening into the melting furnace, said body beingfurther provided with a compressed air container and a duct leadingtherefrom and detachably connected to the compressed air duct of theinsert member.

4. An electric furnace comprising a body having a lower chamber and anupper chamber of greater width than the lower chamber and into which thelatter opens, a flask arranged in the lower chamber and removabletherefrom, an 14 insert member removably mounted in the upper chambersaid ilask being mounted on the bottom of said insert member, a meltingfurnace in the insert member and arranged to discharge molten materialinto the flask, a plate covering 14 the lower chamber and having anopening through which the ilask depends and means detachably securingsaid covering plate, said ilange of the flask and said insert membertogether.

5. An electric furnace comprising a. body hav- 15 ing a lower chamberand an upper chamber of greater width than the lower chamber and intowhich the latter opens, a flask arranged in the lower chamber andremovable therefmm and an insert member removably mounted in the upperchamber said flask being mounted on the bottom of said insert member, amelting furnace in said insert member, and arranged to discharge moltenmaterial into the ilask, said melting furnace having a detachable capprovided with an observation opening.

6. An electric furnace comprising a body having a lower chamber and anupper chamber of greater width than the lower chamber and into which thelatter opens, a flask arranged in the lower chamber and removabletherefrom and an insert member removably mounted in the upper chambersaid flask being mounted on the bottom of said insert member, and aplate covering the lower chamber and having an opening through which theflask depends and means, detachably securing said covering plate, saidange of the ask and said insert member together, the flange of the flaskhaving a groove at its upper side and the lower side of the insertmember being provided with a projecting bead to enter said groove andform a tight joint between said insert member and said ilask.

7. An electric furnace comprising a body having a lower chamber and anupper chamber of greater width than the lower chamber and into which thelatter opens, a flask arranged in the lower chamber, removable therefromand having a. ilange. an insert member removably mounted in the upperchamber, and a plate covering the lower chamber and having an openingthrough which the flask depends and means detachably securing saidcovering plate. said flange of the ask and said insert member together,the flange of the ilask havingv a groove at its upper side and the lowerside of the insert member being provided with a projecting bead to entersaid groove and form a tight joint between said insert member and saidflask, said insert member also having an additional depending ilange andsaid body having a groove around the bottom of the upper chamber inwhich said additional flange is iitted.

RUDOLF lll

